Github user NicoK commented on a diff in the pull request: https://github.com/apache/flink/pull/4533#discussion_r154320189 --- Diff: flink-runtime/src/test/java/org/apache/flink/runtime/io/network/netty/PartitionRequestClientHandlerTest.java --- @@ -244,54 +237,89 @@ public void testCancelBeforeActive() throws Exception { } /** - * Verifies that {@link RemoteInputChannel} is enqueued in the pipeline, and - * {@link AddCredit} message is sent to the producer. + * Verifies that {@link RemoteInputChannel} is enqueued in the pipeline for notifying credits, + * and verifies the behaviour of credit notification by triggering channel's writability changed. */ @Test public void testNotifyCreditAvailable() throws Exception { + final SingleInputGate inputGate = createSingleInputGate(); + final RemoteInputChannel inputChannel1 = spy(createRemoteInputChannel(inputGate)); + final RemoteInputChannel inputChannel2 = spy(createRemoteInputChannel(inputGate)); final CreditBasedClientHandler handler = new CreditBasedClientHandler(); - final EmbeddedChannel channel = new EmbeddedChannel(handler); + final EmbeddedChannel channel = spy(new EmbeddedChannel(handler)); - final RemoteInputChannel inputChannel = createRemoteInputChannel(mock(SingleInputGate.class)); + // Increase the credits to enqueue the input channels + inputChannel1.increaseCredit(1); + inputChannel2.increaseCredit(1); + handler.notifyCreditAvailable(inputChannel1); + handler.notifyCreditAvailable(inputChannel2); --- End diff -- Please use a `BufferResponse` (as above, with an appropriate backlog) to trigger the same result without a new method only used by tests - this will also test more code paths (as suggested).
---